Charged particle beam apparatus and charged particle beam irradiation method

Abstract

A charged particle beam apparatus produces little reduction in resolution when the beam is inclined with respect to a sample. The trajectory of a primary beam 4 is deflected by a deflector or changed by a movable aperture such that the beam is incident on a plurality of lenses 6 and 7 off the axes thereof. A means is provided to control the off-axis trajectory of the beam such than an aberration produced by the objective lens 7 when the beam is inclined can be canceled by an aberration produced by the other lens 6.

1. A charged particle beam apparatus comprising a charged particle source and a charged particle optical system for focusing a charged particle beam emitted from the charged particle source and scanning a sample with the charged particle beam,
 the charged particle optical system further comprising: 
 an objective lens for focusing the charged particle beam and irradiating the sample therewith; 
 a second lens disposed between the objective lens and the charged particle source for irradiating the objective lens with the charged particle beam without producing a crossover between the objective lens and the second lens; 
 a first deflector for deflecting the charged particle beam such that the beam passes through an off-axis of the objective lens so as to irradiate the sample from off the axis of the objective lens and with an inclination; and 
 a second deflector for deflecting the charged particle beam in a direction opposite to the deflecting direction of the first deflector so as to cause the charged particle beam to pass through an off-axis of the second lens and to cancel a coma aberration produced by the objective lens and the second lens. 
 
   
   
     2. The charged particle beam apparatus according to  claim 1 , wherein the first deflector comprises a first coil for deflecting the charged particle beam that passed through the second lens in a direction opposite to the deflecting direction of the second deflector, and a second coil for deflecting the charged particle beam deflected by the first coil toward the objective lens. 
   
   
     3. The charged particle beam apparatus according to  claim 2 , wherein an aperture is disposed between the first coil and the second coil. 
   
   
     4. The charged particle beam apparatus according to  claim 1 , comprising means for applying a negative voltage to the sample. 
   
   
     5. A charged particle beam apparatus comprising a charged particle source and a charged particle optical system for focusing a charged particle beam emitted from the charged particle source and scanning a sample with the charged particle beam,
 the charged particle optical system comprising: 
 an objective lens for focusing the charged particle beam and irradiating the sample therewith; 
 a second lens disposed between the objective lens and the charged particle source for irradiating the objective lens with the charged particle beam without focusing the charged particle beam between the objective lens and the second lens; 
 a first deflector for deflecting the charged particle beam such that the beam passes through an off-axis of the objective lens so as to irradiate the sample from off the axis of the objective lens and with an inclination; and 
 a second deflector for deflecting the charged particle beam in a direction opposite to the deflecting direction of the first deflector so as to cause the charged particle beam to pass through an off-axis of the second lens and to cancel a coma aberration produced by the objective lens and the second lens. 
 
   
   
     6. The charged particle beam apparatus according to  claim 5 , wherein the first deflector comprises a first coil for deflecting the charged particle beam that passed through the second lens in a direction opposite to the deflecting direction of the second deflector, and a second coil for deflecting the charged particle beam deflected by the first coil toward the objective lens. 
   
   
     7. The charged particle beam apparatus according to  claim 6 , wherein an aperture is disposed between the first coil and the second coil. 
   
   
     8. The charged particle beam apparatus according to  claim 5 , comprising means for applying a negative voltage to the sample. 
   
   
     9. A charged particle beam apparatus comprising: a charged particle source; and a charged particle optical system for focusing a charged particle beam emitted from the charged particle source and scanning a sample with the charged particle beam,
 the charged particle optical system further comprising: 
 an objective lens for focusing the charged particle beam and irradiating the sample therewith; 
 a second lens disposed between the objective lens and the charged particle source for irradiating the objective lens with the charged particle beam without producing a crossover between the objective lens and the second lens; 
 a first coil for deflecting the charged particle beam that passed through the second lens; 
 a second coil for deflecting the charged particle beam deflected by the first coil in a direction opposite to the deflecting direction of the first coil so as to irradiate the objective lens off the axis thereof; 
 a third coil for deflecting the charged particle beam emitted from the charged particle source in a direction opposite to the deflecting direction of the first coil; and 
 a fourth coil for deflecting the charged particle beam in a direction opposite to the deflecting direction of the third coil. 
 
   
   
     10. A charged particle beam apparatus comprising a charged particle source and a charged particle optical system for focusing a charged particle beam emitted from the charged particle source and scanning a sample with the charged particle beam,
 the charged particle optical system comprising: 
 an objective lens for focusing the charged particle beam and irradiating the sample therewith; 
 a deflector for deflecting the charged particle beam such that the beam passes through an off-axis of the objective lens so as to irradiate the sample from off the axis of the objective lens and with an inclination; and 
 negative voltage applying means for applying a negative voltage to the sample, 
 wherein an angle of inclination of the charged particle beam is determined by the angle of deflection by the deflector and the negative voltage applied to the sample.